X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml@lancaironline.net Date: Sat, 31 Jan 2009 07:39:40 -0500 Message-ID: X-Original-Return-Path: Received: from imo-d22.mx.aol.com ([205.188.144.208] verified) by logan.com (CommuniGate Pro SMTP 5.2.12) with ESMTP id 3459891 for lml@lancaironline.net; Fri, 30 Jan 2009 00:44:31 -0500 Received: from Sky2high@aol.com by imo-d22.mx.aol.com (mail_out_v39.1.) id q.c85.43da212b (42805) for ; Fri, 30 Jan 2009 00:44:28 -0500 (EST) From: Sky2high@aol.com X-Original-Message-ID: X-Original-Date: Fri, 30 Jan 2009 00:44:27 EST Subject: Re: [LML] Down Flap Relay Failure (Update) X-Original-To: lml@lancaironline.net MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="-----------------------------1233294267" X-Mailer: AOL 9.1 sub 5003 X-Spam-Flag:NO -------------------------------1233294267 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit Tom, I've got to find the wiring diagram. If I remember correctly, part of the circuit is to provide reverse power to instantly stop the motor so it doesn't drift. The magnetic reed switches that sense the up/down limits merely remove power much like the flap switch. In order for the limit switch to fail, you would have had to hold the flap switch in the down position (unless it is not a snap-back switch). Perhaps someone else can explain why the relay contacts would be arcing (stuck) and if that was the cause of the flap motor continuing. There are ways to protect the contacts. I've got to dig out the wiring diagram. The flap pix are interesting as they indicate you were performing as a test pilot. Your judicious use of power certainly saved the day. The nose down pitch would have been increased along with extreme drag and probably no additional lift. I think if you would have fire walled the throttle, control might have been compromised. Side note: I use partial flaps (3 degrees from 160 to 140 KIAS and 10 degree take off flaps from 140 to 110 KIAS) to assist in slowing down and to keep the nose down at those slower speeds. I'm glad the rods weren't bent. I'm sure there would have been some skin damage if this had happened with the flaps going up - and I have no idea about what control issues would have been introduced - especially at slow speed and high AOA. The trim tab looks like it is fully effective at cruise (tab deflected up to keep the nose trimmed down), but the air flow might not work as well when the tab is deflected down (elevator up) because of the disturbed airflow around the screws and over the hinge. Maybe. Of course, the tab could be extended aft if more control is needed. It will be very interesting to learn where the CG is located. Hmmmm, even minor equipment changes often require that the moment be recalculated and logged. The airplane should have been re-weighed when the engine was changed. LNC2's seem to benefit from a more forward CG, especially if they go faster than normal. As such, it could have an effect on trim with the flaps extended that requires adjustment to trim effectiveness as mentioned above. BTW, I have a 12 pound harmonic damper on my flywheel that moved my empty weight CG a bit forward of the recommended range. Anyway, nice flying in that you were sensitive to the control distortions and carefully corrected them with power, etc. Scott Krueger In a message dated 1/29/2009 10:24:29 P.M. Central Standard Time, dudewanarace@yahoo.com writes: In response to Scott Krueger I have come up with a few answers to his well thought out questions. If I could only be as articulate as he is. (My Holiday Inn Express stay is way over due) ** It would be nice to know why the relay got stuck (contacts fused?) so that the cause can be eliminated. It seems that one of the contacts has some sort of buildup on it. This buildup was half way across the intended gap of the contacts. I can only assume this was from the relay arcing. ** Did you later measure the actual flap angle since it was probably larger than 45 degrees if the motor reached its mechanical limit? Such a deployment could explain the lesser effect of the elevator. Yes, sort of. The book calls for 8 or 8.5 inches travel (can't remember) measured from the inner most point of the flap. My flaps were at 11 inches. Not sure what angle that is yet. Pics below: http://www.n54sg.com/stuff/flap01.jpg http://www.n54sg.com/stuff/flap02.jpg ** Were the flap to bell crank push rods bent as the hole thru the rear spar might not have been big enough to handle such an extreme? No That does seem to be the limiting point of the travel, but the breaker popped before any damage was done. In flight I was very concerned about flap limit speed. VFE (Maximum Flap Extended Speed) is 120 MPH, assuming you only have 45 degrees of flaps extended. One can only assume that more flaps equals a lower VFE. Had I firewalled the throttle I think I would have found out what the true VFE is for that amount of flaps. I do know they held up to about 100 MPH indicated. Any slower and I lost pitch up. I was to chicken to go any faster. This was the main reason I DID NOT want to go around. ** Do you trim the elevator with a tab or spring load the whole elevator? If by tab, it might not be as effective at slower speeds. Tab, but a bit bigger than stock tab I think. Pics below: http://www.n54sg.com/stuff/trimtab01.jpg http://www.n54sg.com/stuff/trimtab02.jpg ** What do you estimate as the location of the CG (I assume you still have that heavier engine up front)? It might be too far forward when low on fuel. I have no idea... And this worries me. I was told this engine was +35lbs. But I have also switched from the composite intake to the aluminum, adding a few lbs. I am on the hunt for some scales and someone that knows how to use them. At least get some idea of where the CG is. The log books showing the engine install does not have that information. Tom McNerney www.N54SG.com -- For archives and unsub http://mail.lancaironline.net:81/lists/lml/List.html **************A Good Credit Score is 700 or Above. See yours in just 2 easy steps! (http://pr.atwola.com/promoclk/100000075x1215855013x1201028747/aol?redir=http://www.freecreditreport.com/pm/defa ult.aspx?sc=668072%26hmpgID=62%26bcd=DecemailfooterNO62) -------------------------------1233294267 Content-Type: text/html; charset="US-ASCII" Content-Transfer-Encoding: quoted-printable
Tom,
 
I've got to find the wiring diagram.  If I remember=20 correctly, part of the circuit is to provide reverse power to instantly= =20 stop the motor so it doesn't drift.  The magnetic reed switches th= at=20 sense the up/down limits merely remove power much like the flap switch. = ; In=20 order for the limit switch to fail, you would have had to hold the flap swit= ch=20 in the down position (unless it is not a snap-back switch).  Perha= ps=20 someone else can explain why the relay contacts would be arcing (stuck) = ;and=20 if that was the cause of the flap motor continuing.  There are ways to=20 protect the contacts.  I've got to dig out the wiring diagram.
 
The flap pix are interesting as they indicate you were performing=20= as a=20 test pilot.  Your judicious use of power certainly saved the day. = The=20 nose down pitch would have been increased along with extreme drag and probab= ly=20 no additional lift.  I think if you would have fire walled the throttle= ,=20 control might have been compromised.  Side note: I use partial fla= ps=20 (3 degrees from 160 to 140 KIAS and 10 degree take off flaps from 140 t= o=20 110 KIAS) to assist in slowing down and to keep the nose down at those slowe= r=20 speeds.
 
I'm glad the rods weren't bent.  I'm sure there would have been so= me=20 skin damage if this had happened with the flaps going up - and I have no=20 idea about what control issues would have been introduced - especially=20= at=20 slow speed and high AOA.
 
The trim tab looks like it is fully effective at cruise (tab deflected=20= up=20 to keep the nose trimmed down), but the air flow might not work as well when= the=20 tab is deflected down (elevator up) because of the disturbed airflow around=20= the=20 screws and over the hinge.  Maybe.  Of course, the tab could be=20 extended aft if more control is needed.
 
It will be very interesting to learn where the CG is located.  Hmm= mm,=20 even minor equipment changes often require that the moment be recalculated a= nd=20 logged.  The airplane should have been re-weighed when the engine was=20 changed.  LNC2's seem to benefit from a more forward CG, especially if=20= they=20 go faster than normal.  As such, it could have an effect on trim with t= he=20 flaps extended that requires adjustment to trim effectiveness as mentioned=20 above.  BTW, I have a 12 pound harmonic damper on my flywheel that move= d my=20 empty weight CG a bit forward of the recommended range.
 
Anyway, nice flying in that you were sensitive to the control distortio= ns=20 and carefully corrected them with power, etc. 
 
Scott Krueger
 
 
In a message dated 1/29/2009 10:24:29 P.M. Central Standard Time,=20 dudewanarace@yahoo.com writes:
<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size= =3D2>In=20 response to Scott Krueger I have come up with a few answers to his well=20 thought out questions.  If I could only be as articulate as he i= s.=20 (My Holiday Inn Express stay is way over due)

** It would be nice t= o=20 know why the relay got stuck (contacts fused?) so that the cause can be=20 eliminated.

It seems that one of the contacts has some sort of buil= dup=20 on it.  This buildup was half way across the intended gap of the= =20 contacts.  I can only assume this was from the relay=20 arcing. 

** Did you later measure the actual flap angle since=20= it=20 was probably larger than 45 degrees if the motor reached its mechanical=20 limit?  Such a deployment could explain the lesser effect of the=20 elevator. 

Yes, sort of.  The book calls for 8 or 8.5 in= ches=20 travel (can't remember) measured from the inner most point of the=20 flap.  My flaps were at 11 inches.  Not sure what angle that is=20 yet.  Pics=20 below:
http://www.n54sg.com/stuff/flap01.jpg
http://www.n54sg.com/st= uff/flap02.jpg

**=20 Were the flap to bell crank push rods bent as the hole thru the rear=20= spar=20 might not have been big enough to handle such an extreme?

No =20= That=20 does seem to be the limiting point of the travel, but the breaker popped=20 before any damage was done.  In flight I was very concerned about fla= p=20 limit speed.  VFE (Maximum Flap Extended Speed) is 120 MPH, assuming=20= you=20 only have 45 degrees of flaps extended.  One can only assume tha= t=20 more flaps equals a lower VFE.  Had I firewalled the throttle I think= I=20 would have found out what the true VFE is for that amount of flaps. =20= I do=20 know they held up to about 100 MPH indicated.  Any slower and I lost=20 pitch up.  I was to chicken to go any faster.  This was the main= =20 reason I DID NOT want to go around.

** Do you trim the elevator wit= h a=20 tab or spring load the whole elevator?  If by tab, it might not be as= =20 effective at slower speeds.

Tab, but a bit bigger than stock tab I=20 think.  Pics=20 below:
http://www.n54sg.com/stuff/trimtab01.jpg
http://www.n54sg.com= /stuff/trimtab02.jpg

**=20 What do you estimate as the location of the CG (I assume you still ha= ve=20 that heavier engine up front)?  It might be too far forward when low=20= on=20 fuel. 

I have no idea...  And this worries me.  I wa= s=20 told this engine was +35lbs.  But I have also switched from the compo= site=20 intake to the aluminum, adding a few lbs.   I am on the hunt for= =20 some scales and someone that knows how to use them.  At least get som= e=20 idea of where the CG is.  The log books showing the engine install do= es=20 not have that information.

Tom=20 McNerney
www.N54SG.com

--
For archives and unsub=20 http://mail.lancaironline.net:81/lists/lml/List.html
A Good Credit Score is 700 or Above. See yours in just 2 easy steps!
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